System control carried out through a speech interface based on speech recognition technology is widespread. For example, recently, to allow hands-free operation while driving, in-car systems, such as navigation systems, in-car air conditioners, and in-car audio systems often provide a speech interface. To realize system control through a better speech interface, various types of speech recognition technology have been studied in many areas.
Japanese Unexamined Patent Application Publication No. 2001-312297 discloses a speech recognition apparatus that includes a control unit and a speech synthesis unit.
The control unit gives instructions to a controller for equipment on the basis of a recognized speech command. On the basis of the instructions from the control unit, the speech synthesis unit outputs, from a speech output unit, various kinds of information through speech. When a special command is recognized, the speech recognition apparatus performs conversational guidance processing for explaining how to operate the equipment.
Japanese Unexamined Patent Application Publication No. 2000-267694 discloses a speech recognition apparatus having a speech command group with a hierarchical structure. Each layer of the hierarchical structure of the speech command group includes final speech commands giving final instructions for operation of equipment, and intermediate speech commands giving intermediate instructions and requiring selection of a final speech command at a lower layer for operation of the equipment.
Each layer of the hierarchical structure of the speech command group also includes a speech command for canceling an input speech command or a speech command for terminating speech recognition.
Japanese Unexamined Patent Application Publication No. 2001-63489 discloses a centralized management system for in-car equipment. When a return instruction for canceling an operation instruction is given, the centralized management system checks whether a screen has been changed according to the canceled operation instruction. If the screen has been changed, the centralized management system obtains the latest operation instruction according to which the screen was previously changed, gives an instruction to display a screen, refers to a screen transition history, and displays a screen displayed immediately before the execution of the canceled operation instruction.
Japanese Unexamined Patent Application Publication No. 11-311522 discloses an operation apparatus for in-car equipment. If a right-hand direction is selected when selection areas are displayed on the top, bottom, and left and a combined area is displayed on the right, the operation apparatus generates three separate areas corresponding to functions “Others”, “VICS”, and “FM Multiplex”, allows these three separate areas to be displayed close to each other, and moves the selection areas by a certain distance.
Japanese Unexamined Patent Application Publication No. 11-334483 discloses an in-car equipment control system that includes a front control unit for front seat passengers and a rear control unit for rear seat passengers. The front control unit has functions necessary for driving, and the rear control unit has functions for entertainment purposes. In other words, the in-car equipment control system provides these different control units for the distribution of functions.
Japanese Unexamined Patent Application Publication No. 11-119792 discloses an equipment control apparatus having a speech recognition function and capable of preferably responding to the input of similar type commands. When a similar type command is recognized, the equipment control apparatus determines whether to permit or prohibit the execution of the similar type command on the basis of the current driving conditions. For prohibiting the execution of the similar type command, the equipment control apparatus gives a talk-back to prompt the user to speak again using a paraphrastic command. For permitting the execution of the similar type command, the equipment control apparatus gives a talk-back to prompt the user to use a paraphrastic command from the next time.
Japanese Unexamined Patent Application Publication No. 2001-312297
Japanese Unexamined Patent Application Publication No. 2000-267694
Japanese Unexamined Patent Application Publication No. 2001-63489
Japanese Unexamined Patent Application Publication No. 11-311522
Japanese Unexamined Patent Application Publication No. 11-334483
Japanese Unexamined Patent Application Publication No. 11-119792
Kita, Kenji. Probabilistic Language Model. University of Tokyo Press, 25 Nov. 1999. 34-37, 60-62.
North, Stephen C. “Drawing graphs with NEATO.” Online. 26 Apr. 2004. 8 Aug. 2006<http://www.graphviz.org/Documentation/neatoguide.pdf>.